2020 Land Rover Defender Engine Problems

I am reporting a systemic failure of exhaust manifold retaining bolts on the 2020 Land Rover Defender (L663, P400 engine). While removing the engine skid plate, I discovered a fractured exhaust manifold bolt that had fallen down. The bolt head had separated, leaving the threaded portion in the cylinder head. There are I believe 12 manifold bolts securing the integrated exhaust manifold/turbocharger assembly, & multiple owners have documented similar failures, including cases with multiple broken bolts on one vehicle. The exhaust manifold is integrated with the turbocharger and is part of the emissions control pathway. This assembly operates at extremely high temps. Based on the pattern of failures, repeated thermal cycling and inadequate fastener material appear to cause bolt fatigue and fracture. When bolts break, proper clamping force is lost and hot exhaust gases escape directly into the engine compartment rather than remaining sealed within the manifold/turbo assembly. This presents serious safety concerns: Fire risk: Escaping exhaust gases from a turbocharged engine can exceed 1,000°F. These gases are released near wiring, plastic components, insulation, and other materials. Loss of sealing increases the risk of localized overheating and engine compartment fire. Exhaust gas intrusion: Exhaust leaks at the manifold can allow exhaust gases to enter the passenger compartment. Emissions defect: As this leak occurs upstream of emissions control components, unmetered exhaust gases escape before entering the emissions system, affecting federally regulated emissions compliance. This costs thousands to fix and owners are going to ignore it due to cost & unawareness. Multiple vehicles across varying mileages have experienced this issue, suggesting a systemic design or material defect rather than normal wear. Exhaust manifold fasteners should not fracture under normal operating conditions on a vehicle with 30,000 miles.

Hello! My 2020 P400 Defender is repeatedly not restarting itself at stoplights when the standard auto start/stop functionality engages. Upon removing my foot from the brake pedal to begin moving, what normally happens is thst the engine restarts itself and I drive off as normal. However, at least once or twice a day now, the car does not restart itself, the instrument cluster turns off, and I look down in the car has put itself into Park. I am stopped in traffic etc. This is a somewhat significant fault in my opinion - because it has now happened at busy intersections, highway on ramps, and other places where you do not want people aggressively honking or worse hitting you from behind if they are distracted. I thought perhaps I just needed a software update or something, but my car is confirmed to be on the newest Land Rover software systems for everything in the car. I have not taken it to the dealer for this problem yet (no appts avail) but will be taking it in later this month. The reason I decided to submit this to you is that I went on a Defender group on Facebook, and there are many posts on there with other people in the United States having the exact same problem. With both P300 and P400 engines in Defenders. So I believe this may be a fault with software or hardware (and not just an isolated issue with my Defender… which by the way is my favorite car I’ve ever owned!) — that needs to be rectified with some sense of urgency with Land Rover. Also, my novice testing of why and when this is happening has concluded one workaround that I believe prevents the issue: if I press the button on the dash to turn off the auto start/stop, this problem does not occur. However, the car defaults to auto start/stop being on at each ignition cycle - so that would need to be something that users would need to remember to do each time they started the car.